<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <div id="app">
        <input v-model="username"/>
        <!--插值表达式-->
        {{username}}
    </div>


    <script src="vue.js"></script>
    <script>

        //1.创建Vue核心对象
        //el:"#app" 设置 id为App的div都被控制

        new Vue({
            el:"#app",
            data:function () {
                return{
                    username:""
                }
            }
        })

    </script>
</body>
</html>